Japan and India -- along with Australia and the United States -- are part of the "Quad" alliance, a grouping of regional powers that is increasingly concerned about China's military and economic influence.

Tokyo has held a string of joint military exercises in recent months, as well as overhauling its defence and security strategy and explicitly airing its concerns about China.

In December, Prime Minister Fumio Kishida's government committed to doubling defence spending to two percent of GDP by 2027, and dubbed China the "greatest strategic challenge ever" to Japan's security.

Last week, Japan inked a new defence deal with Britain and agreed to expand its mutual defence treaty with Washington to attacks in space.